This invention relates to a system for recovering nutrients from unusable animal byproducts. More particularly, the invention relates to a complete system for recovering protein and fat from poultry byproducts; however, the system is also amenable to other applications, such as recovering nutrients from beef, pork or fish byproducts. The system also has applications in producing a fertilizer in which the unusable byproducts can be converted into a biomass for application in growing fields for plants and animals.
A traditional system used to convert unusable animal byproducts into usable materials, such as dried protein and raw fats, is based on the action of squeezing water from heated material. The animal byproduct material is transported via truck from an originating site, such as a poultry processing plant, to a rendering plant. In a traditional rendering or byproduct recovery system, the animal byproduct material is loaded into a loading hopper. From the hopper, the material is transferred to a massive pressurized kettle where the material is heated. These cooking kettles collect the material in giant batches and raise the temperature of the material to 160 degrees F. for up to 65 minutes.
In this process, as the material is heated, a conductive energy transfer system takes effect. The surface heat coefficient of the animal byproduct material in the heating kettle is low, therefore the heat transfer rate is high. As heat is transferred into the material, the water and water-based substances in the byproduct begin to vaporize, causing the cell walls to lyse under the increased and sustained partial pressures within the cells. This action releases the water and water-based substances from the solids.
Because the process lasts for up to 65 minutes, the increased heat levels allow the amino acid structures in the animal byproduct material to denature. As proteins denature, the change in carboxyl and carbonyl groups allow more moisture to be driven off, leaving an altered, shorter amino acid chain in the protein structure.
Additionally, the fat molecules in the animal byproduct material are emulsified as a result of this process, and the fats and lipids separate from the solid materials. The fatty acids have the opportunity to separate from the base glycerol, creating an increased possibility of amplified deterioration of the fat materials. Because fats are hydrophobic by nature, they also separate from the water that has been released from the solid materials.
After the moisture is driven off and the material has been transformed into a collection of solid materials, fats, and water, an odor emanates as is natural from cooking biological materials. This odor is cleaned by bio-scrubbers that act as giant baffles that push the positive airflow through wet screens, dry screens and spray heads.
From the cooking kettles, the material is transferred to a squeeze press. Because the kettles process materials in a batch production method, the presses are usually large tables with pressing heads that put top pressure on the material. The principle is to use pressure to squeeze water from the material. Some systems use a wringing system in which the materials that come out of the cooking kettles are passed through a wringer. The wringer is usually designed as two rollers that have a preset space through which the material can pass. The water falls off to the side, and is called “stic water.”
After the pressing or squeezing process, the material can be transferred to a tumble dryer to be sold as a compound feed material, or it can be transferred to a centrifuge to further separate the oils, water, and protein meal. The protein is dried in tumblers and then transferred to a storage bin. The oils are collected in a storage vat for sale to a consumer of raw fats. The wastewater is processed through conventional waste water treatment methods.
The traditional byproduct recovery system is slow and requires significant capital outlays for the large machinery of the system. Not only is the traditional system expensive to set up, it is also expensive to operate. Furthermore, the traditional byproduct recovery system gives off pungent odors and results in a large amount of waste causing environmental problems. The traditional system produces a protein product that has denatured significantly.
Other known animal byproduct processing systems use a dehydrator that is similar to the apparatus described in U.S. Pat. No. 5,105,560, which is incorporated herein by reference. For recovery of nutrients from chicken byproducts, these systems primarily recover the offal or feathers of a chicken. The blood, dead on arrivals (“DOAs”), bones and fat can be discarded or recovered using another method, or can be processed using the same method, either in conjunction with the aforementioned or mutually exclusively from the aforementioned system. By using the aforementioned system to process blood, DOAs and bone materials, the quality of amino acid profiles is significantly reduced as these materials are mostly composed of proteins.
In all scenarios, protein and fat quality is diminished because of the exposure to consistently high temperatures over an extended period of time with regard to individual batches, which is also varied from batch to batch. Also, the end result of compound processing yields a consistent protein and fat product that does not account for the value of individual raw materials.
Accordingly, it is desirable to provide an animal byproduct recovery system that can provide a fresher recycled material at substantially reduced process times. Furthermore, it is desirable to provide a system that has the option to be located on the premises of a processing plant, to obviate the need to transport the animal byproduct. It is also desirable to provide a protein meal that is less denatured than protein meals produced by known methods. Proteins that are less denatured are more digestible by the animal, which results in higher quality growth of the animal. Additionally, it is desirable to provide a system that is more environmentally friendly, as well as other advantages that can be understood by one skilled in the art who reads the following description.